Height adjustable work chairs are used in home, office, education, and industry. These height adjustable chairs typically include a seat that swivels in relation to the base of the chair. The height adjustment is typically obtained from a telescoping spring height adjustment mechanism which is usually a gas spring. This gas spring is a telescoping column that includes a cylinder which includes a pressurized gas such as nitrogen; a piston extending downwardly from the cylinder which supports the cylinder in an elevated position and includes an end which secures the gas spring to the chair base; and a valve located within the cylinder which allows the movement of gas within the cylinder.
The upper section of the cylinder is typically tapered and is secured within a tapered socket within a furniture component support mechanism. The furniture component support mechanism is used to support a furniture component such as a chair seat or table top. If the furniture component support mechanism supports a chair seat, the mechanism may be referred to as a chair seat support mechanism. The chair seat support mechanism is also known as the chair tilt mechanism, particularly on chairs with adjustable backrests or chairs having a tilting chair seat.
Also included in the furniture component support mechanism is a lever that actuates the valve located in the gas spring. The valve typically includes a button extending from the top of the cylinder. When the button is depressed by the lever the pressurized gas within the cylinder is allowed to move through the valve. The cylinder will descend if a force exceeding gas pressure is applied on the spring or raise the cylinder if no force is applied on the spring. The gas spring may additionally include an air or oil damping mechanism which slows the rate of compression and extension for the gas spring.
The gas spring is typically supported in a vertical position between a base and a furniture component support by a vertical stand tube. The stand tube includes a top opening sized so that the cylinder of the gas spring can move vertically and rotationally in relation to the stand tube, yet remain supported by the stand tube regardless of the vertical or rotational position of the cylinder. The stand tube is typically a metal cylinder which includes top and bottom ends. An opening on the top end is included which is sized to accommodate a gas spring cylinder which moves vertically in relation to the stand tube. In some instances a bushing may be disposed within the opening to minimize friction between the gas spring cylinder and the stand tube. The opening serves to both guide the gas spring cylinder as well as to vertically support the gas spring which extends between the chair seat support mechanism and the chair base.
The bottom end of the stand tube cylinder typically is tapered for insertion into a base. The tapered bottom end is typically pressed into a tapered socket at the hub or center of the base. The stand tube bottom typically includes an opening through which the distal end of the piston of the gas spring can extend so as to be secured to the bottom of the stand tube. Typically, a clip type fastener is typically used to secure the distal end of the piston of the gas spring to the bottom of the stand tube.
During assembly of a chair the tapered upper section of the gas spring cylinder is seated, or secured, into the socket of the gas spring support mechanism. Similarly, during the assembly process the tapered end of the stand tube is seated within the tapered socket of the chair base.
During use of the chair, the weight of the chair user is transferred from the chair seat to the chair base through the gas spring/stand tube assembly. Because of this, the tapered upper section of the gas spring cylinder can become very securely pressed into the socket of the gas spring support mechanism.
Replacing a damaged gas spring typically involves the replacement of the entire gas spring/stand tube assembly. For this reason, the tapered upper section of the gas spring cylinder must be released from the socket within the gas spring support mechanism. Additionally, the tapered end of the stand tube must also be released from the chair base. This procedure is required to replace a damaged gas spring such as one which has developed excessive play or one which has lost internal gas pressure.
Release of the gas spring cylinder from the socket of the gas spring support mechanism typically requires a sharp impact force applied to the chair seat. The force of this impact will eventually cause the release of the tapered upper section of the gas spring cylinder from the socket. This impact force, however is transferred directly through the chair seat, and may in result in damage to the chair seat or another chair component.
In the event that the procedure needs to be done in view of the chair owner, the chair owner would watch a hammer wielding technician or sales person disassemble the chair. Multiple hammer blows is hardly the type of treatment that the chair owner expects their expensive chair should receive in this circumstance.
For this reason, there is needed a mechanism which assists the removal of the tapered upper section of the gas spring cylinder from the socket within the furniture component support within which it is secured.
The present invention is a height adjustable pedestal having a gas spring which is easily separated from a furniture component support. The height adjustable pedestal of the present invention can be used in chairs and tables. The present invention also provides a method of releasing the tapered upper section of the gas spring from the socket in which it is retained. The method involves no impact forces. The pry lever can be used to apply a force directly on the top of the gas spring cylinder. The invention allows the gas spring to be released simply without the possibility of damage to the gas spring, or other chair component.
Depending on the type of furniture component support used in the pedestal, access holes which allow for the quick release pry lever to be used are provided within the furniture component support. In some versions of the invention, the access holes provide a surface on which the pry lever can pivot. In other version, a separate pivot surface is provided within the furniture component support. The inclusion of access holes in a chair seat support or other furniture component support does not represent any difficulty for the manufacturer. Because of this, the invention provides significant benefits at little cost to chair assemblies. The invention would work equally well in table assemblies that use telescoping gas spring assemblies.
The present invention greatly eases the process of gas spring replacement as it is performed in height adjustable pedestals. Through the use of the present invention, the chair owner or service technician is ensured that no damage to the chair will result from the release of the gas spring from the furniture component support within which it has been disposed. No damaging hammer blows will be applied to the chair seat.
These and other features and advantages of the present invention will be apparent upon inspection of the following drawings, description, and claims.